UIBestPractice

MainActivity.Class

public class MainActivity extends AppCompatActivity {

    private List<MSG> msgList = new ArrayList<>();
    private EditText inputText;
    private Button send;
    private RecyclerView msgRecyclerView;
    private MsgAdapter adapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
       initMsgs(); //初始化消息数据
        inputText = (EditText) findViewById(R.id.input_text);
        send = (Button) findViewById(R.id.send);
        msgRecyclerView = (RecyclerView) findViewById(R.id.msg_recycler_view);
        LinearLayoutManager layoutManager = new LinearLayoutManager(this);
        msgRecyclerView.setLayoutManager(layoutManager);
        adapter = new MsgAdapter(msgList);
        msgRecyclerView.setAdapter(adapter);
        send.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                String content = inputText.getText().toString();

                if(!"".equals(content)){
                    MSG msg = new MSG(content,MSG.TYPE_SEND);
                    msgList.add(msg);
                    if(content.equals("我爱你") || content.equals("I love you")){
                       // Toast.makeText(MainActivity.this,content,Toast.LENGTH_SHORT).show();
                        MSG message = new MSG("我爱你胜过你爱我",MSG.TYPE_RECEIVED);
                        msgList.add(message);
                    }else if(content.equals("我恨你")){
                        MSG message = new MSG("告诉我,我哪里不好,我可以改的",MSG.TYPE_RECEIVED);
                        msgList.add(message);
                    }else if(content.equals("我不想理你了")){
                        MSG message = new MSG("不要啊,你打我也好,骂我也好,就是不能不理我啊,我错了还不行吗?",MSG.TYPE_RECEIVED);
                        msgList.add(message);
                    }else if(content.equals("你是机器人吗")){
                        MSG message = new MSG("你猜猜看,猜对了我就告诉你",MSG.TYPE_RECEIVED);
                        msgList.add(message);
                    }else if(content.equals("告诉我一个密码吧")){
                        MSG message = new MSG("偷偷告诉你,王德强是世界上最帅的男人!",MSG.TYPE_RECEIVED);
                        msgList.add(message);
                    }
                    adapter.notifyItemInserted(msgList.size()-1);
                    //刷新ListView中的显示
                    msgRecyclerView.scrollToPosition(msgList.size()-1);
                    //将listview定位到最后一行

                    inputText.setText("");//清空输入框中的内容
                }
            }
        });

    }

    private void initMsgs(){
        //初始化几条数据用于在RecyclerView中显示
        MSG msg1 = new MSG("Hello guy.",MSG.TYPE_RECEIVED);
        msgList.add(msg1);
        MSG msg2 = new MSG("Hello. Who is that?", MSG.TYPE_SEND);
        msgList.add(msg2);
        MSG msg3 = new MSG("This is Tom. Nice talking to you.",MSG.TYPE_RECEIVED);
        msgList.add(msg3);
    }
}

MSG Class

public class MSG {
    public static final int TYPE_RECEIVED = 0;
    public static final int TYPE_SEND = 1;
    private  String content;
    private int type;

    public MSG(String content, int type) {
        this.content = content;
        this.type = type;
    }

    public String getContent() {
        return content;
    }

    public int getType() {
        return type;
    }
}

MsgAdapter Class

public class MsgAdapter extends RecyclerView.Adapter<MsgAdapter.ViewHolder> {

    private List<MSG> mMsgList;

    static public class ViewHolder extends RecyclerView.ViewHolder {
        LinearLayout leftLayout;
        LinearLayout rightLayout;
        TextView leftMsg;
        TextView rightMsg;

        public ViewHolder(View View) {
            super(View);
            leftLayout = (LinearLayout) itemView.findViewById(R.id.layout_left);
            rightLayout = (LinearLayout) itemView.findViewById(R.id.layout_right);
            leftMsg = (TextView) itemView.findViewById(R.id.left_msg);
            rightMsg = (TextView) itemView.findViewById(R.id.right_msg);
        }
    }


    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext()).inflate(R.layout.msg_item, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(ViewHolder holder, int position) {
        MSG msg = mMsgList.get(position);
        if (msg.getType() == TYPE_RECEIVED) {
            //如果收到的消息,则显示左边的消息布局,将右边的消息布局隐藏
            holder.leftLayout.setVisibility(View.VISIBLE);
            holder.rightLayout.setVisibility(View.GONE);
            holder.leftMsg.setText(msg.getContent());
        } else if (msg.getType() == TYPE_SEND) {
            //如果是发出的消息,则显示右边的消息布局,将左边的消息布局隐藏
            holder.rightLayout.setVisibility(View.VISIBLE);
            holder.leftLayout.setVisibility(View.GONE);
            holder.rightMsg.setText(msg.getContent());
        }
    }

    @Override
    public int getItemCount() {
        return mMsgList.size();
    }

    public MsgAdapter(List<MSG> mMsgList) {
        this.mMsgList = mMsgList;
    }
}

activity_main Class

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@drawable/background"
    android:orientation="vertical"
    >
    <android.support.v7.widget.RecyclerView
        android:id="@+id/msg_recycler_view"
        android:layout_width="match_parent"
        android:layout_height="0dp"
        android:layout_weight="1"
        ></android.support.v7.widget.RecyclerView>
    <LinearLayout
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <EditText
            android:id="@+id/input_text"
            android:layout_width="0dp"
            android:layout_height="wrap_content"
            android:layout_weight="1"
            android:maxLines="2"
            android:hint="Type something here"
            />
        <Button
            android:id="@+id/send"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:text="Send"
            />
    </LinearLayout>

</LinearLayout>

msg_item.xml

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:orientation="vertical"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:padding="10dp"
    >
    <LinearLayout
        android:id="@+id/layout_left"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:background="@drawable/msg_left"
        android:layout_gravity="left"
        >
        <TextView
            android:id="@+id/left_msg"
            android:layout_margin="10dp"
            android:textColor="#fff"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            />
    </LinearLayout>

    <LinearLayout
        android:id="@+id/layout_right"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="right"
        android:background="@drawable/msg_right">

        <TextView
            android:id="@+id/right_msg"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:layout_gravity="center"
            android:layout_margin="10dp" />
    </LinearLayout>

</LinearLayout>